The present invention relates to a test apparatus for a railway wheel. More specifically, the test apparatus provides an ultrasonic map of the subsurface structure of the wheel for both a quality control analysis of such structure and as a historical record of the structure for post-service analysis.
Railway wheels are generally either wrought or cast steel, although cast iron wheels were utilized during the nineteenth century. Railway wheels, as test pieces, may be broadly described as large, heavy, awkward and cumbersome elements, which may weigh between 700 and 1000 pounds, for example. Analysis and inspection techniques for these wheels generally may be considered to have historically evolved from the following methods: (1) visual inspection; (2) physical testing, including microstructure analysis by destructive testing on a random sampling basis; (3) magnetic particle testing for surface flaws such as "heat checks"; and, (4) ultrasonic testing for microstructure analysis. This historical listing is not exhaustive of all test methods, but it illustrates the progression of the analytical and testing procedures utilized in the analysis of railway wheels.
The initial introduction of an ultrasonic analysis technique for the railway wheel tread face utilized two transducers in various fixed locations in a test stand, which transducers were provided around the tread circumference. A refinement to this initial test apparatus utilized four, and then eight transducers in a similar configuration to provide a more complete analysis of the wheel perimeter. However, this assemblage again utilized discrete locations around the wheel perimeter. Each of these methods utilized only two rim face transducers, and the remaining two, four or eight transducers in the array are arranged to sense a specific wheel component, characteristic or parameter.
As noted above, analytic test techniques are available to describe the microstructure of a wheel. However, the most generally utilized analytic method involves a sample-destructive technique. The ultrasonic technique provides discrete location analysis of subsurface anomalies, but current apparatus cannot consistently reproduce the test on the same wheel, as there is no repetitive specific locating point or reference position. Thus, repeatability of the test and the test results has been a continuing question. As noted above, it is desirable to test a railway wheel for internal soundness or wheel integrity; to establish a wheel history of each wheel; to provide a more sophisticated analytical tool for evaluating a wheel for potential rejection or discard; and, to provide these evaluations through a nondestructive method or test.